Search Results (60)

Waste-to-energy technology plays a crucial role in advancing the circular economy framework, a strategy that contributes to achieving the United Nations Sustainable Development Goals on responsible consumption and production, as well as the provision of affordable and clean energy. Hydrothermal co-liquefaction has emerged as a promising technology for addressing waste material challenges by converting them into valuable biofuels. This review focuses on biomass feedstock classification and provides an overview of hydrothermal co-liquefaction for sustainable waste management and improved energy production. Moreover, the article provides details on integrating other waste treatment methods with hydrothermal liquefaction to promote the circular economy. Research publications from 2015 to 2025 were obtained from Web of Science and Scopus to identify research trends and output across countries and map out future research directions. The retrieved data from Web of Science was analysed for mapping research, keyword occurrence, and network analysis using VOSviewer software. The study highlighted that waste treatment techniques not only mitigate environmental pollution but also provide a sustainable pathway for energy production and contribute to global carbon neutrality. The review shows that biocrude yield varies with blending ratio because of differences in the biochemical composition of feedstocks, which affect reaction pathways and lead to synergistic or antagonistic interactions during co-processing. Therefore, careful selection of biomass feedstock is essential to achieve optimal results. Full article

Sustainable nanotechnologies derived from renewable resources are increasingly being positioned at the interface of green chemistry, advanced drug delivery, and translational pharmaceutics. Over the past decade, lignocellulosic nanomaterials, chitin/chitosan platforms, polysaccharide-based nanogels and nano-enabled hydrogels, lignin- and polyphenol-derived nanostructures, and bio-based lipid nanocarriers have been engineered through progressively eco-efficient routes, including solvent-minimized self-assembly, nanoprecipitation, spray drying, hot-melt extrusion, and microfluidic-assisted fabrication. This work provides a structured evidence map of nano-enabled drug delivery and therapeutic platforms derived from renewable biological resources. Specifically, we aim to (i) identify and classify nanoplatform classes and renewable feedstocks; (ii) summarize reported pharmaceutical critical quality attributes (CQAs) and performance and safety endpoints; and (iii) appraise how “renewability” and “green” claims are evidenced (feedstock origin vs. process sustainability) and how frequently translational readiness factors (scalability, quality control, regulatory alignment) are addressed. We critically compare renewable and conventional nanomaterial platforms across key translational dimensions, including carbon footprint, batch consistency, biodegradability, functional tunability, safety/persistence, and scale-up maturity. Finally, we delineate a practical translational pathway—from biomass sourcing and fractionation to nanoformulation, characterization/stability, and GMP scale-up—highlighting cross-cutting enablers such as lifecycle assessment, EHS/toxicology risk assessment, quality-by-design, and regulatory alignment. Collectively, the evidence supports renewable nanomaterials as viable, scalable candidates for next-generation therapeutics, provided that variability control, standardized characterization, and safety-by-design principles are embedded early in development. Full article

Thermal hydrolysis pretreatment (THP) increases the solubilization of sewage sludge, while bioelectrochemically assisted anaerobic digestion (BEAD) enhances the conversion of the solubilized organic matter into methane and improves reactor stability in the presence of inhibitory compounds. In this study, by mapping methane production in a BEAD reactor against the soluble organic loading rate (sOLR), determined from soluble chemical oxygen demand (sCOD) measurements, distinct operational regimes corresponding to different THP temperatures were identified. With the 120 °C pretreated feedstock, the BEAD reactor operated in a hydrolysis-limited regime, where increasing sOLR increased methane production but reduced conversion efficiency. Accordingly, at an sOLR of 4.5 g (L_R d)⁻¹, a volumetric methane production rate of 0.8 L L_R⁻¹ was achieved. Increasing THP severity to 150 °C improved solids solubilization and shifted the system into a kinetically enhanced regime, in which methane production was directly proportional to sOLR, indicating improved substrate accessibility and reaction kinetics. Consequently, at an sOLR of 7.75 g (L_R d)⁻¹, methane production reached 1.46 L L_R⁻¹. This regime-based analysis provides quantitative guidance for selecting pretreatment severity and loading strategies to maximize methane production, while maintaining stable BEAD reactor operation at high organic loads. Full article

Non-recyclable plastic waste (PSW) and residual lignocellulosic biomass (WP) represent abundant yet underused resources whose conversion can generate renewable fuels with synergistic benefits. While conventional pyrolysis remains limited by slow heat transfer and poor adaptability to heterogeneous feeds, microwave-assisted pyrolysis (MAP) offers faster volumetric heating and improved syngas quality, though it is still largely confined to the laboratory scale due to limited understanding of feedstock interactions and process behaviour. In this context, the present work provides a laboratory-scale experimental investigation of the MAP co-pyrolysis of PSW/WP blends, focusing on gas yield and syngas quality, and complements the experimental analysis with a preliminary scale-up assessment for a continuous microwave reactor. The results reveal clear synergistic effects, with gas yields exceeding those predicted by linear mixing. A 70/30 wt% PSW/WP blend produced a hydrogen-rich syngas with H₂ concentrations of approximately 42 vol% and an H₂/CO ratio of 2–3. Compared to conventional pyrolysis under analogous conditions, MAP increased hydrogen content by around 35% and reduced CO₂ concentrations by up to 40%, resulting in a cleaner and more energy-dense gas. Overall, the findings highlight the strong potential of MAP for the valorization of mixed plastic–biomass wastes. Full article

Biopolymers from renewable sources are increasingly explored to reduce the carbon footprint of materials and mitigate plastic pollution. This review synthesizes the last five years of progress across the biopolymer value chain, comparing plant, microbial/fermentation, fungal, and marine/algal resources and critically assessing greener extraction and fractionation routes (ultrasound and microwave intensification, subcritical water, supercritical CO₂ with co-solvents, ionic liquids, deep eutectic solvents including natural deep eutectic solvents, and enzymatic or bio-mediated processes). We emphasize yield-selectivity trade-offs, scalability, energy demand, and solvent recovery. Downstream, we summarize purification and performance tuning via crosslinking, derivatization, blending/plasticization, and nanocomposites, and we map advanced characterization to targeted functional properties to bridge processing choices with end-use performance. Applications are organized across food and agriculture, biomedical and pharmaceutical technologies, packaging, and cosmetics, with cross-cutting attention to safety and regulatory compliance, quality-by-design, techno-economics, and life-cycle assessment. Key bottlenecks are feedstock variability, viscosity and recyclability limitations of designer solvents, and persistent gaps in barrier and thermal properties versus petrochemical benchmarks, compounded by uneven composting and recycling infrastructure. Promising directions include low-viscosity or switchable solvents, data- and artificial intelligence (AI)-guided process optimization, engineered biopolymers, and circular end-of-life strategies that align material design with realistic recovery routes. Full article

European bioeconomy policies stress the need for responsible, efficient feedstock use and timely, comprehensive data on ecosystems and bioeconomic activities. This paper addresses the data gap by: (i) providing holistic county-level (sub-NUTS3) biomass maps for the Republic of Ireland (RoI), covering primary feedstocks (PFs) and secondary feedstocks (SFs, i.e., by-products and waste); (ii) identifying feedstock uses during the study period. In total, 221 feedstocks were mapped: 85 solid PFs (approx. 43 million tonnes dry matter (tDM) nationally) and 136 solid SFs (approx. 6 million tDM nationally), plus 6 liquid PFs (approx. 18 thousand million m³ nationally) and 8 liquid SFs (approx. 39 thousand million m³ nationally). The mapping indicates that environmentally sustainable bio-based value chains (BBVCs) requiring large amounts of solid or liquid SF should prioritise processing sites near major feedstock sources in the southeast and southwest of the RoI. The northwest and east coast have the lowest availability, while the west and midlands have the most variety in quantity and type of feedstock. Counties with abundant feedstocks do not necessarily have high feedstock diversity, except for Cork. Granular sub-NUTS3 mapping of quantities and fate provides a powerful foundation for future feedstock strategies and empowers stakeholders to design innovative BBVCs. Full article

Second-generation bioethanol from food industry lignocellulosic residues offers a promising route toward low-carbon, circular bioenergy systems. However, the reported environmental impacts differ markedly across studies, challenging efforts to assess the true sustainability of these waste-derived bioethanol routes. This review synthesizes current knowledge on the production of bioethanol from key agro-industrial wastes including oil palm empty fruit bunches, sugarcane bagasse, brewers’ spent grain, spent coffee grounds, tea waste, citrus residues, and potato peel waste. We outline feedstock characteristics, availability, and prevailing management practices, and map the principal biochemical conversion routes to identify process steps that drive environmental performance. A systematic comparison of life cycle assessments reveals substantial methodological heterogeneity across functional units, system boundaries, allocation procedures, and impact assessment methods. Nonetheless, consistent hotspots emerge, particularly associated with pretreatment severity, enzyme production, thermal energy demand, and co-product handling. The review highlights robust cross-study trends, pinpoints methodological gaps, and proposes recommendations for harmonized LCA practice. By integrating technological and methodological perspectives, this work aims to support the development and policy uptake of sustainable, waste-based bioethanol within circular bioeconomies. Full article

Achieving decarbonization targets in the aviation sector requires transformative approaches to sustainable aviation fuel (SAF) production. In this pursuit, feedstock innovation has emerged as a critical challenge. This research uses the U.S. SAF Grand Challenge as a case study, focusing on its feedstock innovation workstream, to investigate how Industry 4.0 technologies can fulfill that workstream’s objectives. An integrative literature review, drawing on academic, industry, and policy sources, is used to evaluate the Technology Readiness Levels (TRLs) of Industry 4.0 technology applications across the SAF biomass supply chain. The analysis identifies several key technologies as essential for improving yield prediction, optimizing resource allocation, and linking stochastic models to techno-economic analyses (TEAs): IoT-enabled sensor networks, probabilistic/precision forecasting, and automated quality monitoring. Results reveal an uneven maturity landscape, with some applications demonstrating near-commercial readiness, while others remain in early research or pilot stages, particularly in areas such as logistics, interoperability, and forecasting. The study contributes a structured TRL-based assessment that not only maps maturity but also highlights critical gaps and corresponding policy implications, including data governance, standardization frameworks, and cross-sector collaboration. By aligning digital innovation pathways with SAF deployment priorities, the findings offer both theoretical insights and practical guidance for advancing sustainable aviation fuel adoption and accelerating progress toward net-zero aviation. Full article

Sustainable aviation fuel (SAF) has demonstrated significant potential to reduce carbon emissions in the aviation industry. Multiple national and international initiatives have been launched to accelerate SAF adoption, yet large-scale commercialization continues to face technological, operational, and regulatory barriers. Industry 4.0 provides a suite of advanced technologies that can address these challenges and improve SAF operations across the supply chain. This study conducts an integrative literature review to identify and synthesize research on the application of Industry 4.0 technologies in the production and distribution of SAF. The findings highlight that technologies such as artificial intelligence (AI), Internet of Things (IoT), blockchain, digital twins, and 3D printing can enhance feedstock logistics, optimize conversion pathways, improve certification and compliance processes, and strengthen overall supply chain transparency and resilience. By mapping these applications to the six key workstreams of the SAF Grand Challenge, this study presents a practical framework linking technological innovation to both strategic and operational aspects of SAF commercialization. Integrating Industry 4.0 solutions into SAF production and supply chains contributes to reducing life cycle greenhouse gas (GHG) emissions, strengthens low-carbon energy systems, and supports the United Nations Sustainable Development Goal 13 (SDG 13). The findings from this research offer practical guidance to policymakers, industry practitioners, investors, and technology developers seeking to accelerate the global shift toward carbon neutrality in aviation. Full article

Anaerobic digestion (AD) has long been valued for producing a biogas–digestate pair, yet its profitability is tightening. Next-generation AD biorefineries now position syngas both as a supplementary feedstock and as a springboard to capture high-value intermediates, hydrogen (H₂) and volatile fatty acids (VFA). This review dissects how complex natural consortia “decide” between hydrogenogenesis and acetogenesis when CO, H₂, and CO₂ co-exist in the feedstocks, bridging molecular mechanisms with process-scale levers. The map of the bioenergetic contest between the biological water–gas shift reaction and Wood–Ljungdahl pathways is discussed, revealing how electron flow, thermodynamic thresholds, and enzyme inhibition dictate microbial “decision”. Kinetic evidence from pure and mixed cultures is integrated with practical operating factors (gas composition and pressure, pH–temperature spectrum, culture media composition, hydraulic retention time, and cell density), which can bias consortia toward the desired product. Full article

Polyvinyl chloride (PVC) recycling poses significant engineering challenges and opportunities, particularly regarding material integrity, energy efficiency, and integration into circular manufacturing systems. This systematic review evaluates recent advancements in mechanical innovations, tooling strategies, and intelligent technologies reshaping PVC recycling. An emphasis is placed on machinery-driven solutions—including high-efficiency shredders, granulators, extrusion moulders, and advanced sorting systems employing hyperspectral imaging and robotics. This review further explores chemical recycling technologies, such as pyrolysis, gasification, and supercritical fluid extraction, for managing contamination and additive removal. The integration of Industry 4.0 technologies, notably digital twins and artificial intelligence, is highlighted for its role in predictive maintenance, real-time quality assurance, and process optimisation. A combined PRISMA approach and ontological mapping are applied to classify technological pathways and lifecycle optimisation strategies. Critical engineering constraints—including thermal degradation, additive leaching, and feedstock heterogeneity—are examined alongside emerging innovations, like additive manufacturing and microwave-assisted depolymerisation, offering scalable, low-emission solutions. Regulatory instruments, such as REACH and Extended Producer Responsibility (EPR), are analysed for their influence on machinery compliance and design standards. Drawing from sustainable manufacturing frameworks, this study also promotes energy efficiency, eco-designs, and modular integration in recycling systems. This paper concludes by proposing a digitally optimized, machinery-integrated recycling model aligned with circular economy principles to support the development of future-ready PVC reprocessing infrastructures. This review serves as a comprehensive resource for researchers, practitioners, and policymakers, advancing sustainable polymer recycling. Full article

This article provides an overview of various microwave-assisted techniques, such as microwave-assisted extraction (MAE), microwave-assisted organic synthesis (MAOS), microwave-assisted pyrolysis (MAP), microwave-assisted hydrothermal treatment (MAHT), microwave-assisted acid hydrolysis (MAAH), microwave-assisted organosolv (MAO), microwave-assisted alkaline hydrolysis (MAA), microwave-assisted enzymatic hydrolysis (MAEH), and microwave-assisted fermentation (MAF). Microwave-assisted biomass pretreatment has emerged as a promising method to improve the efficiency of biomass conversion processes, in particular microwave-assisted pyrolysis (MAP). The focus is on microwave-assisted pyrolysis, detailing its key components, including microwave sources, applicators, feedstock characteristics, absorbers, collection systems, and reactor designs. Based on different studies reported in the literature and a mathematical model, a mechanical design of a microwave oven adapted for pyrolysis is proposed together with a computer-aided design and a finite element analysis. The semi-continuous system is designed for a 40 L capacity and a power of 800 W. The material with which the vessel was designed is suitable for the proposed process. The challenges, opportunities, and future directions of microwave-assisted technologies for the sustainable use of biomass resources are presented. Full article

This systematic map explores the role of sustainability certification schemes and labels in reducing greenhouse gas emissions across biobased value chains. With increasing global and EU interest in transitioning to a sustainable bioeconomy, these certification mechanisms are seen as critical tools for promoting low-emission practices. This review maps the available evidence regarding the effectiveness of certification schemes, examining sector-specific variations and identifying knowledge gaps. A comprehensive search strategy was employed across three major databases and grey literature sources, yielding 41 relevant articles. There are significant disparities in the evidence on the impact of sustainability certification schemes and labels on greenhouse gas (GHG) emissions across biobased sectors. Agriculture has the most data, but studies are heavily focused on organic systems, limiting broader conclusions. Most research is concentrated in Southeast Asia and Europe, reducing generalizability to other regions. Additionally, most studies focus on the production stage, leaving value chain phases like processing and disposal under-represented. Knowledge gaps exist across sectors, certification schemes, and life cycle stages, highlighting the need for further research. While some schemes incorporate GHG management tools, evidence on their effectiveness remains insufficient and context-dependent, warranting more robust, targeted research. Though this research looked at all biobased feedstocks, it did not review schemes and labels specifically targeting biofuels, which presents an avenue for future research. Full article

Hydrothermal liquefaction (HTL) is an effective biomass thermochemical conversion technology that can convert organic waste into energy products. However, the HTL process is influenced by various complex factors such as operating conditions, feedstock properties, and reaction pathways. Machine learning (ML) methods can utilize existing HTL data to develop accurate models for predicting product yields and properties, which can be used to optimize HTL operation conditions. This paper presents a bibliometric review on ML applications in HTL from 2020 to 2024. CiteSpace, VOSviewer, and Bibexcel were used to analyze seven key bibliometric attributes: annual publication output, author co-authorship networks, country co-authorship networks, co-citation of references, co-citation of journals, collaborating institutions, and keyword co-occurrence networks, as well as time zone maps and timelines, to identify the development of ML in HTL research. Through the detailed analysis of co-occurring keywords, this study aims to identify frontiers, research gaps, and development trends in the field of ML-aided HTL. Full article

Green chemistry refers to the design and application of practices that prevent pollution and promote environmental sustainability. A set of 12 principles make up the core of the green chemistry philosophy, and, since their emergence, they have been implemented in the educational practice of tertiary education. Over the past few years, the green chemistry approach has started expanding among secondary education as well. This review discusses green chemistry teaching experiences in secondary education as reported in 70 scientific publications (from 2002 to the present) that were identified via a literature search. All identified documents were examined and analyzed to map their green chemistry content and relevant environmental issues, the degree of the connection between the chemistry concepts and environmental issues (“environmentalization”), the implemented teaching-learning approaches, and, when applicable, the achieved learning outcomes. Analysis showed that all 12 green chemistry principles were covered within the identified publications, with the ones referring to prevention and the use of renewable feedstocks being the most frequent. The publications touch upon several environmental issues, with the most frequent being those referring to hazardous chemical waste, alternative energy resources, and recycling. Most of the publications correspond to a medium degree of environmentalization. The inquiry-based, hands-on-based, problem-based, context-based, and socio-scientific issues-based teaching approaches were shown to be the most widely used. Regarding the achieved learning goals, those mostly explored were related to the cognitive and affective domains. This comprehensive review may provide a solid foundation for the organization and design of novel curricula that will integrate green chemistry into education for sustainable development programs in secondary education. Full article